Having established the structure of the keto sugar precursor to the 3,6-dideoxy hexoses in Pasteurella pseudotuberculosis as 3,6-dideoxy-D- erythro-hexos-4-ulose, we propose to study the stereochemical nature of the products of the enzymatic reduction of CDP-6-deoxy-4-keto-D-glucose into CDP-3,6-dideoxy-D-erythro-hexos-4-ulose. Detection of 4-amino-4-6- dideoxy-hexoses in natural sources, investigation of their structural relationships at the molecular level and their biological importance are also included in this proposal. We will synthesize derivatives of a new class of amino sugars, 4-amino-3,4,6-trideoxyhexoses.